Operating unit for vehicle

ABSTRACT

The operating unit for a vehicle is provided with a housing with a front face and an operating element which is arranged on the front face of the housing and has an operating surface. The operating element is mounted in a spring-elastic manner. Furthermore, at least one sensor is provided for detecting an actuation movement of the operating element. The operating unit additionally has at least one actuator for the feedback movement of the operating element in the case of an actuation movement of the operating element detected by the sensor as well as an analysis and control unit which is connected to the at least one sensor and to the actuator. The actuator is designed as an armature-type electromagnet with a first stator which has a first excitation coil, and an armature as a drive element. Furthermore, the armature is provided with a measuring coil to which a measuring voltage is applied when the magnetic flux generated by the first excitation coil flows through the armature. The first excitation coil and the measuring coil are connected to the analysis and control unit, and with the analysis and control unit it is possible to apply open-loop and/or closed-loop control to the force with which the armature of the actuator can move towards the first stator and/or the deflection movement of the armature out of its rest position and the return movement of the armature back into its rest position are adapted to be controlled and/or regulated.

The invention relates to an operating unit for a vehicle, which may bean infotainment system for operating various vehicle components, forexample.

Operating units having display assemblies on which, for example, varioussymbol fields are adapted to be represented in a menu-driven manner viawhich the functions for a vehicle component can be selected by effectiveactuation, e. g. pressing (also referred to as force sense), arebecoming more and more popular. The operator is to receive a tactileconfirmation of the selection of a function in the form of an additionalactive movement of the operating element after its activation (so-calledforce feedback), for example.

From DE-A-10 2008 035 907 and DE-A-10 2012 000 568 touch-sensitive inputdevice are known. From DE-A-10 2009 007 243 a laterallyspring-elastically mounted operating element of an input device isknown. Further in DE-A-100 43 805 an electromechanical actuator for thevalve operation of an internal combustion engine is disclosed, whereinthe actuator is provided with a measuring coil.

For installation space and cost reasons an electromagnet (armature-typemagnet) without permanent magnets is frequently employed as an actuator.The stator of such an armature-type magnet is thus to beelectromagnetically operated. For adjusting the desired movement of theoperating surface of the operating element the temporal forceprogression at the actuator must be exactly adjustable. In addition, itmay be required that the force by means of which the operating elementis moved forwards and backwards is respectively actively built up. Thismay be realized by means of a double armature-type magnet having acommon armature between two electromagnetic stators.

In the case of slowly varying magnetic fields the force of anelectromagnet essentially depends on the armature current and the airgap between the armature and the stator. The force progression in thecase of the haptic feedback is hover ever very dynamic and comprisesfrequency components above 1 kHz. Here, the connection between currentand force in the case of normally used machining steels or electricalsheets for guiding the magnetic flux is not trivial and can only bedescribed by a very complex modeling. In addition, the air gap is notexactly known due to the mechanical tolerances and the movement of theoperating surface, therefore the force action of an armature-type magnetcan only be roughly estimated.

It is an object of the invention to provide a relatively exact andinexpensive force measurement in an actuator configured as anelectromagnet for the haptic feedback from operating elements of anoperating unit for a vehicle. For this purpose the electromagnet may beconfigured as a single armature or a double armature.

For achieving this object the invention suggests an operating unit for avehicle, wherein the operating unit is provided with

-   -   a housing having a front face,    -   an operating element arranged on the front face of the housing,        which comprises an operating surface, wherein the operating        element is spring-elastically mounted,    -   at least one sensor for detecting an actuation movement of the        operating element,    -   at least one (e. g. electromagnetic or piezoelectric) actuator        for a feedback movement of the operating element in the case of        an actuation movement of the operating element detected by the        sensor, and    -   an analysis and control unit which is connected to the at least        one sensor and the actuator.

According to the invention, in such an operating unit it is providedthat

-   -   the actuator is configured as an armature-type electromagnet        having a first stator comprising a first excitation coil and an        armature as a drive element,    -   the armature is provided with a measuring coil to which a        measuring voltage is applied when a magnetic flux generated by        the first excitation coil flows through the armature, and    -   the first excitation coil and the measuring coil are connected        to the analysis and control unit, wherein by means of the        analysis and control unit the force is adapted to be controlled        and/or regulated with the aid of which the armature of the        actuator is adapted to be moved towards the first stator and/or        with the aid of which the deflection movement of the armature        out of its rest position as well as the return movement of the        armature into its rest position are adapted to be controlled        and/or regulated.

With the approach according to the invention for measuring the magneticflux flowing through the armature by means of a measuring coil and theinduced voltage dropping at the latter, the force and the movement ofthe armature can be controlled and/or regulated. Further, the movementof the armature can be purposely dampened such that an overshooting inthe respective end position of the forward and backward movement of thearmature can be avoided.

It may further be advantageous when the armature is arranged between twoelectromagnetically operated stators. In this embodiment of theinvention, the armature thus comprises a second stator having a secondexcitation coil, wherein the two stators are arranged on both sides ofthe armature and the second excitation coil is also connected to theanalysis and control unit, wherein by means of the analysis and controlunit the respective force is adapted to be controlled and/or regulatedwith the aid of which the drive element is adapted to be moved in therespective direction towards the first and/or the second stator and/orthe deflection movement of the drive element out of its rest position aswell as the backward movement of the drive element into its restposition are to be controlled and/or regulated.

For realizing as homogeneous as possible a haptic feedback across theoverall operating surface the operating unit may advantageously beprovided with

-   -   a housing having a front face    -   an operating element arranged on the front face of the housing,        which comprises a center of gravity and an operating surface,    -   wherein the control element is spring-elastically mounted at        and/or in the housing along a vertical movement axis essentially        extending orthogonally to the operating surface and along a        lateral movement axis essentially extending transversely with        respect thereto,    -   at least one sensor for detecting an actuation movement of the        operating element in the direction of the vertical movement        axis,    -   an actuator mounted in and/or at the housing for a feedback        movement of the operating element at least also along the        lateral movement axis in the case of a recognized actuation        movement of the operating element, wherein the actuator        comprises a drive element adapted to be electromagnetically        controlled and mechanically coupled with the operating element,        which is adapted to be moved forwards and backwards along an        effective movement axis, and    -   an analysis and control unit which is connected to the sensor        and the actuator,    -   wherein the center of gravity of the operating element lies on        the effective movement axis of the drive element of the        actuator.

According to this aspect of the invention, the active haptic feedback ofan actuation of the operating element is realized by a lateraldeflection of the operating element. For actuation purposes theoperating element is moved along a vertical movement axis essentiallyextending orthogonally to the operating surface. If the sensor detectsthis actuation movement (force sense) an active movement of theoperating element (force feedback) e. g. in a lateral movement directionor with a movement component in a lateral direction (e. g. by amechanical excitation along a direction at an acute angle to theoperating surface e. g. to the left or to the right, upwards ordownward) is carried out. Care must be taken that the operating elementdoes not tilt. The operating element essentially comprises a displayhaving a corresponding display design and technology (LCD display, forexample) and backlighting such that it may have a considerable overallinstallation depth. Since in the ideal case the actuator may at best bearranged directly beneath this operating element, its drive elementengages with the latter in the lateral movement direction outside thecenter of gravity of the operating element for performing an activehaptic feedback movement. Without any corresponding measures thisinevitably results in a tilting of the operating element, which isundesired. Known solutions aim at a forced guide with a correspondingdesign of the spring system by means of which the operating element ismounted to the housing of the operating unit. This involves a largemechanical effort.

Therefore this aspect of the invention provides for the operatingelement and the actuator to be mechanically arranged such that they arealigned relative to each other in such a way that the center of gravityof the operating element lies on the effective movement axis of thedrive element. On the extension of the effective movement axis of thedrive element thus lies the center of gravity of the operating element.The effective movement axis of the drive element thus extends at anacute angle to the intended lateral movement direction for the activehaptic feedback. Due to the operating element being moved along theeffective movement axis of the drive element the feedback movement ofthe operating element comprises a vertical movement component besidesthe lateral movement component, but this has no disturbing effect.Rather, it is crucial that the operating surface of the operatingelement maintains its alignment in the space for the active hapticfeedback, that is experiences a transverse parallel displacement.

It can thus generally be said that due to the excitation of theoperating element for the haptic feedback the resultant movement of theoperating element in the form of a lateral main movement and a secondarymovement normal to the operating surface is carried out. Depending onthe attack angle of the excitation the magnitude of the normal movementcomponent may vary. Thus, as a rule, no pure lateral movement takesplace.

This measure allows for the active haptic feedback movement to becarried out in a purely translatory manner (with vertical and lateralmovement components) in that the effective direction of the driveelement passes through the center of gravity of the operating element.

Rotatory movement components in the haptic feedback of the operatingelement are further reduced by the return spring elements, with the aidof which the operating elements are returned into the initial positionafter an active haptic feedback, lying in a common plane with the centerof gravity of the operating element. Here, the effective spring axescoincide with the effective movement axis of the drive element of theactuator. If this were not the case, the pattern of the active hapticfeedback movement of the operating element would comprise rotatorycomponents. For installation space reasons the effective axes of thesprings typically extend in parallel to the effective movement axis ofthe drive element of the actuator on both sides of this effectivemovement axis, whereby unwanted moments, which might act upon theoperating element during its return movement into the initial position,are neutralized to a large extent.

Further, it is advantageous to actively control or regulate the hapticsin a forward and return path. For this purpose it is also crucial thatthe movement of the operating element is purely translatory, ifpossible, which can be realized with the approach according to theinvention. Further, the approach according to the invention essentiallyensures that the haptic sensation is always the same independent of theactuation location on the operating surface. According to the invention,complex constructive solutions for spring mounting of the operatingelement such that the latter executes a purely translatory movement areno longer required.

It is appropriate when the lateral movement axis of the operatingelement and the effective movement axis of the drive element of theactuator span a common vertical plane extending essentially orthogonallyto the operating surface.

According to another aspect of the invention it may be provided that thehousing comprises an installation space beneath the operating elementand that for achieving the smallest possible angle between the effectivemovement axis of the drive element of the actuator and the lateralmovement axis of the operating element the actuator is arranged as nearas possible beneath the operating element as allowed by the installationspace and/or as far away as possible from the center of gravity of theoperating element as allowed by the installation space. The smaller theangle between the effective movement axis of the actuator and thelateral movement axis of the operating element, the larger is thelateral movement component of the operating element with respect to thelateral movement component of the feedback movement.

According to another aspect of the invention, the operating unitcomprises return spring elements for the operating element havingeffective spring axes arranged on both sides of the operating elementwhich lie on the lateral movement axis or in a plane which extendsessentially orthogonally to the plane spanned by the effective movementaxis of the drive element of the actuator and the lateral movement axisof the operating element and are arranged symmetrically to the lateralmovement axis.

Hereunder the invention is described in detail on the basis of anexemplary embodiment with reference to the drawings in which:

FIG. 1 schematically shows a side view of an operating unit for avehicle component having an operating element configured as a displayelement and spring-elastic mounting as well as an active haptic feedbackfor actuating the operating element,

FIG. 2 shows a diagram of an electromagnet configured as anarmature-type magnet having a stator and an armature for basicallyexplaining the electromagnetically relevant properties of such anelectromagnet,

FIG. 3 shows a perspective diagram of the actuator configured as adouble electromagnet for the active haptic feedback, and

FIG. 4 shows a possible circuit configuration of the electromagnet asper FIG. 3.

In FIG. 1 a schematic side view of an operating unit 10 comprising anoperating element 12 is shown. In this exemplary embodiment, theoperating element 12 is configured as a display assembly having anoperating surface 14 on which a plurality of symbol fields 16 areadapted to be represented. As a rule, the operating element 12 isbacklit.

For executing an actuation movement in a vertical movement direction(see double arrow 18) as well as for confirming such an actuationmovement in a lateral direction (see double arrow 20 in FIG. 1) theoperating element 12 is elastically mounted at a housing 26 via firstsprings 22 as well as second springs 24. A sensor 28 can determine thatthe operating element has moved along the vertical movement axis 18.This is ascertained in an analysis and control unit 30, where-upon thelatter controls an actuator 32 configured as an electromagnet whichcomprises a drive element 34. The fixed stator portion 36 of theactuator 32 is supported on the housing 26 while the drive element 34 ofthe actuator 32 is mechanically coupled with the operating element 12.The effective movement axis of the drive element 34 is shown by thedouble arrow 38.

The larger and more complex the design of the operating element 12, theheavier it is and the more installation space it occupies. If it isrequired that the haptic feedback is the same across the overalloperating surface 14, the operating element 12 should exclusivelyexecute a translatory movement for the haptic feedback. Theoretically,this can be realized in a very simple manner in that the drive element34 of the actuator 32 engages in the center of gravity 40 of theoperating element 12. However, the given installation space does notallow for this.

If it is still intended that the operating element 12 exclusivelyexecutes a translatory movement for the haptic feedback, a comparativelysimple design solution is to arrange the actuator 32 such that thecenter of gravity 40 of the operating element 12 lies on the effectivemovement axis 38 of the drive element 34 of the actuator 32. This isshown in FIG. 1, wherein FIG. 1 also illustrates how the operatingelement 12 actively moves when an actuation movement is recognized andthe actuation of the operating element 12 is confirmed by a hapticfeedback. It should be noted here that the second spring elements 24and/or their effective spring axes 42 ideally lie in a plane in whichthe center of gravity 40 is also located and in which the effectivemovement axis 38 of the actuator 32 lies, wherein the effective axes ofthe actuator 32 and the second springs 24 lie on a common line or extendin parallel to the effective axis 38 of the actuator 32 (in FIG. 1 thisis indicated by the dashed double arrows 42).

Essentially orthogonally to this plane 44 extends that plane that isspanned by the lateral movement axis 20 of the operating element 12 andthe effective movement axis 38 of the drive element 34 of the actuator32. With reference to FIG. 1 this plane is the drawing plane.

The purely translatory movement of the operating element 12 for thehaptic feedback thus comprises both a lateral and a vertical component.The fact that this feedback movement is not purely lateral is of noimportance regarding the fact that the haptic sensation is to be thesame across the overall operating surface 14 of the operating element12. It is crucial that the operating element 12 does not execute anyrotatory movement for the haptic feedback, that is that there is aparallel displacement of the operating element 12 in the space.

As has already been described above, in particular for installationspace and cost reasons an electromagnet is often used as an actuator forthe haptic feedback of operating elements. The force applied by thiselectromagnet can be estimated only at an increased effort andessentially depends on the current and the air gap of the electromagnet.The applicable conditions in the case of an electromagnet arehereinafter elucidated on the basis of FIG. 2.

In FIG. 2 an electromagnet is illustrated whose stator and armature aremade of highly permeable materials (usually machining steel orelectrical sheet) and whose magnetic field is built up by means of anenergized excitation coil.

The force of such an electromagnet is usually calculated from theexcitation current and the size of the air gap. The force progression inthe case of the haptic feedback is however very dynamic with frequencycomponents above 1 kHz. Here, the connection between current and forcein the case of the normally used machining steels or electrical sheetsfor guiding the magnetic flux is not trivial and can only be describedby a very complex modeling. In addition, the air gap is not exactlyknown due to the mechanical tolerances and the movement of the operatingsurface and therefore the force action of the actuator can only beroughly estimated. By the use of the “Maxwell tensile strength formula”and a measuring coil for determining the magnetic flux density in theair gap this problem can be avoided, wherein, as a rule, a voltagemeasurement is more inexpensive than a current measurement:

$F = \frac{B_{L}^{2}A_{L}}{2\; \mu_{0}}$

(F—actuator force, μ₀—permeability of the air, A_(L)—air gap surface,B_(L)—magnetic flux density in the air gap)

The relatively low inhomogeneity of the air gap flux density inpractical applications can be accounted for by a correction factor,which, in turn, leads to a simple realization of a force measurement bymeans of a measuring coil:

${F(t)} = {\frac{C}{\mu_{0}A_{L}}\left( {\frac{1}{N_{MS}}{\int_{0}^{t}{{u\left( t^{\prime} \right)}{dt}^{\prime}}}} \right)^{2}}$

(t—time, C—air gap correction factor, N_(MS)—number of windings of themeasuring coil, u(t)—induced voltage in the measuring coil)

The integration of the induced voltage can be digitally carried out witha microcontroller which normally exists in the system. Thus the force isknown at any time during the control process.

FIG. 3 shows a perspective view of the actuator 32. This actuator 32 isconfigured as a double electromagnet whose drive element 34 serving asan armature 46, which is arranged between a first stator 48 and a secondstator 50, can build up a force in two opposite directions along theeffective movement axis 38.

The first and the second stator 48, 50 are fastened to the housing 26,while the armature 46 is fixedly connected to the operating element 12.The first stator 48 comprises a first excitation coil 52, while thesecond stator 50 is provided with a second excitation coil 54. Thearmature 46 is surrounded by a measuring coil 56. On both sides of thearmature 46 a first and a second air gap 58, 60 are respectivelylocated. Since the force acting upon the armature 46 is respectively tobe directed in one direction the excitation coils 52, 54 are notenergized simultaneously but alternately. The arrangement of themeasuring coil 56 at the armature 46 allows for an exact and inexpensiveforce measurement in both effective directions along the effectivemovement axis 38.

As an example, the control and the analysis of the voltage induced inthe measuring coil 56 may be carried out by means of a microcontroller62 which may form part of the analysis and control unit 30. An exampleof a circuit configuration including the microcontroller 62 is shown inFIG. 4. The induced voltage in the measuring coil 56 is at firstsmoothed by a simple low pass 64 to eliminate from the measured signalthe PWM clocking (frequency normally >20 kHz) for alternatelycontrolling the two excitation coils 52, 54. Thereafter themicrocontroller 62 detects the induced voltage and digitally integratesit. The limiting frequency of the low pass 64 should be sufficientlyhigher than the highest frequency components of the force progression.

LIST OF REFERENCE NUMERALS

-   10 Operating unit-   12 Operating element-   14 Operating surface of the operating element-   16 Symbol fields-   18 Vertical movement axis of the operating element-   20 Lateral movement axis of the operating element-   22 Spring elements-   24 Spring elements-   26 Housing-   28 Sensor-   30 Control unit-   32 Actuator-   34 Drive element of the actuator-   36 Stator portion of the actuator-   38 Effective movement axis of the actuator-   40 Center of gravity of the operating element-   42 Effective spring axis-   44 Plane-   46 Armature-   48 Stator-   50 Stator-   52 Excitation coil-   54 Excitation coil-   56 Measuring coil-   58 Air gap-   60 Air gap-   62 Microcontroller-   64 Low pass

1-2. (canceled)
 3. An operating unit for a vehicle component, inparticular an infotainment system for operating various vehiclecomponents, having a housing having a front face, an operating elementarranged on said front face of said housing, which comprises anoperating surface, wherein said operating element is spring-elasticallymounted, at least one sensor for detecting an actuation movement of saidoperating element, at least one actuator for a feedback movement of saidoperating element in the case of an actuation movement of said operatingelement detected by said sensor, and an analysis and control unit whichis connected to said at least one sensor and said actuator, wherein saidactuator is configured as an armature-type electromagnet having a firststator comprising a first excitation coil, and an armature as a driveelement, said armature is provided with a measuring coil to which ameasuring voltage is applied when a magnetic flux generated by saidfirst excitation coil flows through said armature, and said firstexcitation coil and said measuring coil are connected to said analysisand control unit, wherein by means of said analysis and control unit theforce is adapted to be controlled and/or regulated with the aid of whichsaid armature of said actuator is adapted to be moved towards said firststator and/or with the aid of which the deflection movement of saidarmature out of its rest position as well as the return movement of saidarmature into its rest position are adapted to be controlled and/orregulated.
 4. The operating unit according to claim 3, wherein thearmature-type electromagnet comprises a second stator having a secondexcitation coil, wherein the two stators are arranged on both sides ofthe armature, and wherein said second excitation coil is also connectedto the analysis and control unit, wherein by means of said analysis andcontrol unit the respective force is adapted to be controlled and/orregulated with the aid of which said armature is adapted to be movedinto the respective direction towards the first and/or the second statorand/or the deflection movement of said armature out of its rest positionas well as the return movement of said armature into its rest positionare adapted to be controlled.